Guiding catheters are instruments that allow a physician to access and cannulate vessels in a patient's heart for conducting various medical procedures, including venography and implanting of cardiac pacing devices. Cannulating heart vessels often requires navigating a small diameter, flexible guide through the convoluted vasculature into a heart chamber, and then into a destination heart vessel. Once the destination heart vessel is reached, the catheter acts as a conduit for insertion of payloads into the heart vessel.
A commonly accessed destination vessel for cardiac pacing lead insertion is the coronary sinus. A pre-shaped guiding catheter is typically used to blindly locate the coronary sinus ostium, but this endeavor is complicated by the fact that the location of the coronary sinus ostium may vary appreciably from one patient to another, especially among patients with diseased hearts. Oftentimes, the clinician is entirely unable to locate the coronary sinus ostium using the guiding catheter, and must resort to finding the ostium by “mapping” (interpreting localized unipolar or bipolar waveforms) using an electrophysiological (EP) catheter and an ECG monitor. After the ostium is located, the guiding catheter can be used to inject radiographic contrast media into the coronary sinus to highlight the associated venous system, and then a pacing lead is installed within one of the coronary branches.
Complicating this scenario is the dynamic structural deformation of the heart chambers that occurs from normal cardiac activity during the procedure. This further increases the difficulty of guiding a catheter to its destination. Presently, a considerable amount of time is often spent by the physician when manipulating such catheters within cardiac structures, such as the right atrium, simply trying to locate an anatomical feature of interest, such as the coronary sinus ostium.
Guiding catheter systems are typically configured with a profile that is optimized for the intended method of access. In the case of accessing the coronary sinus via the right atrium, a catheter with a distal contour including a relatively sharp bend will point the catheter towards the likely location of the coronary sinus once the right atrium is reached. The contours of pre-shaped guiding catheters are generally fixed, and this is typically achieved in production by constraining the distal end within a shaping fixture while warming them until they assume the intended shape (i.e., by “heat setting” their polymer shaft).
A fixed shape catheter is adequate in many cases where the pathway is not significantly convoluted and the pathway does not deviate significantly between patients. In situations where structural anomalies or significant variations exist, use of a fixed shape catheter may require that the clinician stock multiple size and shapes of catheters to account for potential variations. Fixed shape catheters may require a time consuming trial and error process of inserting and removing different shapes until the destination vessel is successfully accessed.
Steerable catheters are also used for various guiding applications. Steerable catheters typically rely on an integral steering mechanism that includes a mechanical linkage to a deflection point at the catheter's distal end. These devices can be effective in allowing dynamic reshaping of the catheter's distal end, however they are not ideal for all situations. The linkage takes up space within the catheter's lumen, leaving less space within the catheter for payloads. The linkage usually has some clearance within the lumen to allow for easier longitudinal movement of the linkage. The clearance can result in backlash when the steering mechanism is operated. Depending on the length and deployed shape of the catheter, backlash of a steered catheter may render it difficult to operate.
There is a need for an improved guiding catheter having a simple means of adjusting the distal end shape for venous access and cannulation. There exists a further need for a guiding catheter that provides an adjustable distal end shape while maximizing available payload space within the guiding catheter. The present invention fulfills these and other needs, and addresses other deficiencies of prior art implementations.